Object Storage Service:Copier (Go SDK V2)

Usage notes

• The sample code in this topic uses the region ID cn-hangzhou, which specifies the China (Hangzhou) region. By default, a public endpoint is used to access resources in a bucket. If you want to access resources in the bucket from other Alibaba Cloud services in the same region as the bucket, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.

• In this topic, access credentials are obtained from environment variables. For more information about how to configure the access credentials, see Configure access credentials.

• To copy an object, you must have the read permissions on the source object and read and write permissions on the destination bucket.

• The source bucket and destination bucket must be located in the same region. For example, objects in a bucket located in the China (Hangzhou) region cannot be copied to a bucket located in the China (Qingdao) region.

• Make sure that no retention policies are configured for the source bucket and the destination bucket. Otherwise, the following error message is returned: The object you specified is immutable.

Methods

Introduction to Copy Manager

If you want to copy an object from a bucket to another bucket or modify the attributes of an object, you can call the CopyObject operation or the UploadPartCopy operation. The two operations are suitable for different scenarios:

• The CopyObject operation is suitable only for copying an object smaller than 5 GiB.

• The UploadPartCopy operation is suitable for copying an object that is equal to or greater than 5 GiB in size. Take note that the operation does not support the x-oss-metadata-directive and x-oss-tagging-directive directives. To configure metadata and tagging during a multipart copy operation, you need additional implementation.

The Copier module hides the operation differences and implementation details, providing a universal solution for copying objects. The Copier automatically selects an appropriate operation to copy objects according to the specified request parameters. The following lines provide common methods of the Copier module:

type Copier struct {
  ...
}

// Create a Copier.
func (c *Client) NewCopier(optFns ...func(*CopierOptions)) *Copier

// // Copy objects.
func (c *Copier) Copy(ctx context.Context, request *CopyObjectRequest, optFns ...func(*CopierOptions)) (*CopyResult, error)

Request parameters

Common parameters of CopyObjectRequest

Common parameters of CopierOptions

Response parameters

Sample code

The following sample code provides an example on how to copy an object from the source bucket to a destination bucket and modify the object attributes:

package main

import (
	"context"
	"flag"
	"log"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

// Define the global variables.
var (
	region         string // The region.
	srcBucketName  string // The name of the source bucket.
	srcObjectName  string // The name of the source object.
	destBucketName string // The name of the destination bucket.
	destObjectName string // The name of the destination object.
)

// Use the init function to initialize parameters.
func init() {
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	flag.StringVar(&srcBucketName, "src-bucket", "", "The name of the source bucket.")
	flag.StringVar(&srcObjectName, "src-object", "", "The name of the source object.")
	flag.StringVar(&destBucketName, "dest-bucket", "", "The name of the destination bucket.")
	flag.StringVar(&destObjectName, "dest-object", "", "The name of the destination object.")
}

func main() {
	// Parse parameters.
	flag.Parse()

	// Check whether the source bucket name is empty.
	if len(srcBucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}

	// Check whether the region is empty.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// If the destination bucket name is not specified, the source bucket name is used.
	if len(destBucketName) == 0 {
		destBucketName = srcBucketName
	}

	// Check whether the source object name is empty.
	if len(srcObjectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, src object name required")
	}

	// Check whether the destination object name is empty.
	if len(destObjectName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, destination object name required")
	}

	// Create an OSS client configuration.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	// Create an OSS client.
	client := oss.NewClient(cfg)

	// Create a Copier.
	c := client.NewCopier()

	// Create a request to copy the object.
	request := &oss.CopyObjectRequest{
		Bucket:            oss.Ptr(destBucketName),  // The name of the destination bucket.
		Key:               oss.Ptr(destObjectName),  // The name of the destination object.
		SourceKey:     oss.Ptr(srcObjectName), // The name of the source object.
		SourceBucket:      oss.Ptr(srcBucketName),   // The name of the source bucket.
		StorageClass: oss.StorageClassStandard, // Set the storage class of the destination object to Standard.
		MetadataDirective: oss.Ptr("Replace"), // Ignore the metadata of the source object.
		TaggingDirective:  oss.Ptr("Replace"),       // Ignore the tags of the source object.
	}

	// Copy the object.
	result, err := c.Copy(context.TODO(), request)
	if err != nil {
		log.Fatalf("failed to copy object %v", err) // In case of an error, log the error and exit the operation.
	}

	// Display the result of the operation.
	log.Printf("copy object result:%#v\n", result)
}

References

• For the API operation of the copy manager, see Copy.

• OSS SDK for Go - Developer Guide